1. Field of the Invention
This invention relates to document management systems that manage electronic documents and copyright. This application is based on patent application No. Hei 9-139358 filed in Japan, the content of which is incorporated herein by reference.
2. Prior Art
In general, the conventional document management system that manages the document produced by the document production device is designed to manage attributes of the document such as the title of the document, author (or writer) and date to produce the document. However, the conventional document management system is not designed to manage the copyright information used for management of the copyright. As the distribution of the electronic documents becomes popular, there occur a number of cases that infringement of the copyright of the document occur. To protect the copyright, it is necessary to equip the document management system with the mechanism for protection of the copyright.
One example of the method for protection of the copyright is disclosed by the paper of Japanese Patent Application, Publication No. Hei 8-190545, which is entitled "Document Management System". According to the technology of this paper, there is provided a copyright management information storage unit, which stores only one copyright management information corresponding to the full text of the document in connection with the document ID. Herein, the copyright management information is constructed by multiple processing conditions that represent comments such as "copy allowed" and "print disallowed". When receiving a request that a user who produces a document wishes to use another document produced by another person, the system refers to copyright management information of another document to provide a decision that the use of another document is permissible or impermissible. Thus, it is possible to protect the copyright.
However, the conventional technology described above is incapable of managing the document which has different copyrights with respect to construction units (or constituent elements) of the document such as the chapter, paragraph, sentence, figure and table respectively. For example, the conventional technology cannot perform fine management of the copyrights with respect to the case where the sentence is permissible in copy while the photograph is impermissible in copy. Because, the conventional technology is designed to merely perform copyright management with respect to the selected unit of the document.